1) Technical Field of the Invention
This invention relates to a driving method of an AC type plasma display panel.
2) Description of Related Arts
FIG. 8A shows a cross sectional view of a conventional AC type surface discharge plasma display panel 1 (referred to as the xe2x80x9cconventional panelxe2x80x9d hereinafter), and FIG. 8B shows an another cross sectional view taken along line Axe2x80x94A in FIG. 8A.
As shown in FIGS. 8A and 8B, the conventional panel 1 comprises, in general, a forward substrate 3 and a back substrate 4, both made of glass, opposing to each other through a discharge space 2.
The forward substrate 3 includes a plurality of scan electrodes 7 and sustain electrodes 8, arranged parallel to each other on the lower surface thereof. A dielectric layer 5 covers across the lower surface and the scanning and sustain electrodes 7, 8 as well. A protective layer 6 covers on the dielectric layer 5. The scan electrode 7 and the sustain electrode 8 are made of transparent electrodes 7a, 8a and metal bus 7b, 8b for enhancing conductivities of the electrodes.
The back substrate 4 includes a plurality of data electrodes 9 on the upper surface thereof, and a plurality of partition walls partitioning each data electrode 9. The back substrate 4 further includes fluorescent layer provided on the upper surface thereof, the data electrodes 9, and the sides of the partition walls 10. The forward and back substrates 3, 4 are arranged so that the scan electrodes 7 and the sustain electrodes 8 oppose orthogonally to data electrodes 9. Thus, a plurality of linear discharge spaces 2 are defined by the forward and back substrates 3, 4 and a plurality of partition walls 10.
Gas such as neon, xenon, or the mixture thereof is filled in the discharge space 2, which allows to emit ultraviolet rays in accordance with the electric discharge (referred to as simply xe2x80x9cdischargexe2x80x9d hereinafter).
In such a panel 1, an external-sustain voltage VSUS is alternately applied on each of the scan electrode 7 and the corresponding sustain electrode 8 so as to cause gas in the discharge space 2 to emit ultraviolet rays when the discharge is generated, thereby to excite the fluorescent layer to transform ultraviolet rays into visual rays.
This is a conventional mechanism for displaying as a plasma display panel, and such a discharge is referred to as a xe2x80x9cdisplay dischargexe2x80x9d. The display discharge is also referred to as the xe2x80x9csurface dischargexe2x80x9d generated between the scan electrode 7 and the sustain electrode 8. A distance between the scan electrode 7 and the sustain electrode 8 is determined so that an external-sustain voltage VSUS that can sustain the discharge therebetween is minimized. The distance is referred to as a xe2x80x9cdischarge sustain gap dpxe2x80x9d.
According to the currently available conventional panel, in case where gas within the discharge space 2 has a pressure in the range of about 50 to 60 kPa, and the discharge sustain gap dp falls within the range of 80 to 100 xcexcm, then the external-sustain voltage VSUS is minimized to 180 to 200V. In that case, it is known that the maximum emitting efficiency can be obtained where the partial pressure of xenon gas is 5 to 10% of the total pressure.
However, the conventional panel yet has an insufficient emitting efficiency in comparison with other displays such as CRTs. For example, the aforementioned panel has the maximum emitting efficiency of approximately 11 m/W, which is one-fifth of that of CRTs.
It is well known that the longer discharge sustain gap dp enhances the emitting efficiency, but increases the external-sustain voltage VSUS. Eventually, it is difficult to drive such a panel with higher emitting efficiency.
This invention is ad dressed to this problem and has an object to provide an AC type plasma display panel with higher emitting efficiency without increasing the external-sustain voltage VSUS, even if the discharge sustain gap dp is extended, as well as a method of driving the same.
In a driving method of an AC type plasma display panel according to the first aspect of the present invention, the AC type plasma display panel comprises: a first substrate including a plurality pairs of a first and second electrodes extending parallel to each other on a first surface, and a dielectric layer covering across the first surface and on the first and second electrodes; and a second substrate including a plurality of third electrodes extending on a second surface in a direction crossing the first and second electrodes, and a plurality of partition walls partitioning each third electrode from another; wherein said first and second substrates are arranged so that the first and second surfaces oppose to each other; and said driving method comprising: driving said AC type plasma display panel so that the discharge generated in a first opposing discharge space between a first and third electrodes moves towards a second opposing discharge space between a second and third electrodes, and extends along the third electrode. Therefore, the positive column discharging can be achieved so that the high emission efficiency can be obtained.
In the driving method of the AC type plasma display panel, said AC type plasma display panel further comprises a blue, green, and red fluorescent layers provided on the third electrodes between adjacent partition walls, emitting a blue, green, and red visual rays, respectively, in accordance with ultraviolet rays generated by the discharge; and at least one of widths between the adjacent partition walls provided with the blue, green, and red fluorescent layers are different from others. Therefore, any desirable color light can be obtained.
In the driving method of the AC type plasma display panel, the adjacent partition walls provided with the blue fluorescent layer have the width greater that those provided with green and red fluorescent layers. Therefore, a color temperature of a white light can be adjusted by selecting the widths between the adjacent partition walls.
In a driving method of an AC type plasma display panel according to the second aspect of the present invention, the AC type plasma display panel comprises: a first substrate including a plurality pairs of a first and second electrodes extending parallel to each other on a first surface, and a dielectric layer covering across the first surface and on the first and second electrodes; and a second substrate including a plurality of third electrodes extending on a second surface in a direction crossing the first and second electrodes, and a plurality of partition walls partitioning each third electrode from another; wherein said first and second substrates are arranged so that the first and second surfaces oppose to each other; said driving method comprises the steps of: a) applying a predetermined voltage between the first and second electrodes so that the second electrode is positively biased relative to the first electrode, and applying a data pulse voltage to the third electrode during an address period; and b) applying voltages during an sustain period so that after the discharge begins in a second opposing discharge space between the second and third electrodes, it moves towards a first opposing discharge space between the first and third electrodes, and extends along the third electrode. Therefore, the AC type plasma display panel can be driven with reduced discharging voltages in a stable way.
The driving method of the AC type plasma display panel, further comprises the step of: c) applying voltages so that after the discharge begins in the first opposing discharge space, it moves towards the second opposing discharge space, and extends along the third electrode.
In the driving method of the AC type plasma display panel, said step b) and said step c) are repeatedly and alternately performed so as to sustain the discharge.
In the driving method of the AC type plasma display panel, the voltages applied during the sustain period are less than the minimum voltage necessary for generating a surface discharge between the first and second electrodes.
The driving method of the AC type plasma display panel, further comprises the step of: d) applying a signal voltage with a gradually varying inclined portion to the first, second, or third electrode during an initialize period prior to the address period.
In the driving method of the AC type plasma display panel, the inclined portion has a varying rate of 10 V/xcexcs or less.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the sprit and scope of the invention will become apparent to those skilled in the art from this detailed description.